Use libdbus for trays on Linux instead of Ayatana and GTK

[eafton]

WIP implementation of a pure libdbus tray implementation, should close #13666, #11703 and Taiko2k/Tauon#1772.

Notes:
-Some of the menu interfaces are unimplemented for now.
-Tray creation, icon/tooltip setting works properly.
-Menu export and callbacks are working.
-DestroyTray does not clean up memory for menus and entries.
-Various TODOs in the code are present.
-Canonical's protocol is used for menu export, the GIO menu protocol is unsupported.
-Currently there is no support for the old XEmbed tray protocol, that will come once more "toolkit" functionality (see #14395) gets implemented. Functionality for having multiple tray drivers is already implemented.
-Tooltips are supported unlike the old Ayatana implementation.

@ssokolow @smcv @slouken

[sezero]

Whitespace and style changes are making it difficult to read the actual changes.

Tiny patch to make it build on alder systems:

diff --git a/src/core/linux/SDL_dbus.h b/src/core/linux/SDL_dbus.h
index 738fc06..27dcd41 100644
--- a/src/core/linux/SDL_dbus.h
+++ b/src/core/linux/SDL_dbus.h
@@ -38,6 +38,9 @@
 #ifndef DBUS_TYPE_UNIX_FD
 #define DBUS_TYPE_UNIX_FD ((int)'h')
 #endif
+#ifndef DBUS_ERROR_UNKNOWN_PROPERTY
+#define DBUS_ERROR_UNKNOWN_PROPERTY "org.freedesktop.DBus.Error.UnknownProperty"
+#endif
 
 typedef struct SDL_DBusContext
 {

[eafton]

+#ifndef DBUS_ERROR_UNKNOWN_PROPERTY
+#define DBUS_ERROR_UNKNOWN_PROPERTY "org.freedesktop.DBus.Error.UnknownProperty"
+#endif

Implemented.

[eafton]

Menu export works now, I just gotta wire it up.

[C0rn3j]

Will this implementation count with being able to use scroll events?

Currently we use it to set volume up/down based on scroll up/down over the tray (albeit the support for that in the current tray ecosystem seems spotty).

https://github.com/Taiko2k/Tauon/blob/e943bef475eb555b6bd5769e02ec7f11f80d2d54/src/tauon/t_modules/t_dbus.py#L269-L289

[ssokolow]

If I'm understanding the SDL docs correctly, the SDL API having its guts rewritten currently only exposes the ability to define a context menu and set an icon and tooltip.

(Which matches what I'm seeing in the diff where a quick Ctrl+F shows no mention of the D-Bus SecondaryActivate or Scroll signals... SecondaryActivate being middle click under KDE.)

[eafton]

Will this implementation count with being able to use scroll events?

Currently we use it to set volume up/down based on scroll up/down over the tray (albeit the support for that in the current tray ecosystem seems spotty).

https://github.com/Taiko2k/Tauon/blob/e943bef475eb555b6bd5769e02ec7f11f80d2d54/src/tauon/t_modules/t_dbus.py#L269-L289

If the maintainers approve, we can add this.

@slouken

[slouken]

Will this implementation count with being able to use scroll events?
Currently we use it to set volume up/down based on scroll up/down over the tray (albeit the support for that in the current tray ecosystem seems spotty).
https://github.com/Taiko2k/Tauon/blob/e943bef475eb555b6bd5769e02ec7f11f80d2d54/src/tauon/t_modules/t_dbus.py#L269-L289

If the maintainers approve, we can add this.

@slouken

Sure, we can add this. Go ahead and create a separate follow-on PR once this lands and include Windows support as well.

Thanks!